Detachable bit for coal augers and the like



July 8, 194 1. 7 QR. ANDERSON DETACHABLE BIT FOR COAL AUGERS AND THELIKE Filed July-12, 1939 2 Sheets-Sheet i INVENTOR Cec i Z J? .Andersonu y 3, 1941- c. R. ANDERSON I 2,248,733

DETACHABLE BIT 'FOR COAL AUGERS AND THE LIKE Fild July 12, 1939 2Sheets-Sheet 2 1 a A 27 2325 V 2] I I 4/ I INVENTOR Ce all? .25..Anderson M, MW M Patented July 8, 1941 DETACHABLE BIT FOR COAL scenesAND THE LIKE Cecil B. Anderson, Pittsburgh, Pa., assignor to TheMartin-Hardsocg' Company, Pittsburgh, Pa, a corporation of PennsylvaniaApplication July 12, 1939, Serial No. 284,016

10 Claims.

This invention relates to earth-boring tools and is for a detachable bitconstruction especially adapted for use in the boring of coal and likerelatively soft formations.

It has heretofore been proposed to use a head it the working end of acoal auger having renovable or detachable bits capable of being renovedand sharpened from time to time and reilaced when necessary.Considerable trouble has ween encountered in connection with suchdeices, however, due to the difli-culty of keeping 1e detachable bitstight in the working heads 1 which they are mounted or, when they areufli'ciently tight so that they do not chatter, dif- -.culty has beenencountered in accomplishing the ready removal of them.

According to the present invention there is )rovided a detachable bitcomprising a working lead or body adapted to be secured to the front andof a coal auger wherein the bits are tightly acid in a working positionin the body but from which the bits may be readily removed when it isnecessary to sharpen or replace them. According to the presentinvention, a common means passing transversely to the longitudinal axisof the auger holds the bits against endwise movement and at the sametime applies pressure in a direction transverse to the axis of the augertending to spring the bits or wedge them into tight frictional contactwith the walls of the sockets in which they are received to therebyprevent the bits from chattering or vibrating. The invention may bereadily understood by reference to the accompanying drawings in whichFigure 1 is a side elevation of a portion of the coal auger and adetachable bit construction embodying my invention;

Figure 2 is a similar View at right angles to Figure '1;

Figure 3 is working head, the bit elements being shown in elevation;

Figure 4 is a transverse section in the plane of line IV-IV of Figure 3;

Figure 5 is a front end view of the working head with the detachable bitelements removed;

Figure 6 shows a modification, the view showing the auger in ele ationand the working head in longitudinal section, the bits being shown inelevation;

Figure '7 is a View similar to one of still a further modification;Figure 8 is a View similar to Figure '3 of the modification shown inFigure '7; and

a longitudinal section through the Figure 9 is also a longitudinalsection similar to Figure 8 but showing the bits only partially insertedin the holder.

Referringto the drawings and particularly to Figures 1 to 5, 2designates the end portion of a coal auger which may be of any preferredconstruction. It is provided with a squared terminal portion 3. 4designates the working head which is secured to the end of the auger 2and which carries the detachable bits 5 and 6. The head 4 is preferablyformed of malleable cast steel and is of a generally twisted formproviding spiral flutes or ribs 1 having a pitch conforming generally tothe pitch of the flanges on the coal auger. It is provided with a squaresocket 8 at its rear end into which the squared projection 3 on the endof the auger 2 extends, and it is further provided with shoulders 9which abut against the flanges of the auger for further holding the headand auger against relative rota tion.

In the opposite or front end of the working head 4 are two slot-likesockets Ill located diagonally opposite each other on opposite sides ofthe center of rotation of the working head. These slots extend inwardlyinto the body 4 at an angle to the longitudinal axis of the assembly.The slots pass entirely through the enlarged portion 4A at the front ofthe body 4 and termiri'ate at shoulders 42) (see Figure 3). The body 4at :a point intermediate its ends is so narrowed that the inner ends ofthe slots adjacent the shoulders 4b open at opposite sides of the head,as shown in Figure 3.

The cutters 5 and 6 are formed of pieces of steel of generallyrectangular cross section, the cross section of the shanks of thecutters 5 and 6 being of the shape and approximate size of the slots itso that the shanks may be received in the slots with the ends of theshanks of the cutters abutting against the shoulders 42). The frontterminal portions of the cutters are properly shaped toform cuttingsurfaces. By reason of the inclination of the slots It with reference tothe longitudinal axis of the assembly, the shanks of the cutters crossone another as shown in Figure 1, but they are separated by anintervening solid body of metal indicated at 40 in Figure 3. Passingdiametrically through the enlarged end part do of the head 4 is atapered key-way 4d. This key-way is located at approximately the pointwhere the longitudinal center lines of the shanks of the two bits crosseach other. Each bit preferably has a shallow channel ll formed on theinner face of its shank positioned to coincide with this key-way. Atransverse key l2 having a slight taper toward one end is driven intothe opening 4d from one side of the head and, as shown in Figure 4, ispreferably of a length such that its terminal portion 12a projects aslight distance beyond the side face of the head at the other side ofthe head from which it is entered. The transversely extending key l2 hastwo functions. First, being received in the channel or grooves H in theshanks of the bits, it prevents the bits from being pulled out of thehead 4 in an endwise direction. Secondly, by reason of its slight taper,it tends to spread the shanks of the two bits apart in a directiontransverse to the longitudinal axis of the assembly thereby causing thebits to be wedged outwardly against the confining walls of the slots andthus held from chattering or vibrating.

To remove the bits it is merely necessary to tap the projecting end I2aof the key l2 to drive the key out of the key slot. If the bits cannotthen be easily removed, the inner ends of the bits where they abutagainst the shoulders 4b are exposed and by inserting a screwdriver orother wedging implement between the ends of the bits and the shoulders4b, they can be readily 100sened and thus be removed;

The slots forming the sockets are inclined with respect to thelongitudinal axis, as best shown in Figure l, in order to enablesubstantially straight cutter bits to be used and get the proper degreeof spread or flare for the end of the unit. If desired, these two holesor sockets may, as shown in Figure 3, also converge outwardly to aslight extent so as to bring the cutting portions of the bits intoproper relation with one another.

In the embodiment of the invention shown in Figure 6, the bit-carryingmember or working head I5 is of the general form shown in Figure 1 andfits onto the end of the auger 2' in the same way. Its working end isprovided with an enlarged part He, and there are two slots l5 thereinpositioned similarly to the slots I and inclined in a similar mannerwith reference to the longitudinal axis of the assembly. Into each ofthe slots I is inserted the shank of a cutter I1, the cutters also beinggenerally of the form shown in Figures 1 and 2. Between the two slots 16there is a body of solid metal l5b. The working head is so formed thatextensions of the slots I6 beyond the portion I511 of the body arechannels which receive the inner ends of the bits, these channelsterminating in shoulders I50 against'which the ends of the bits abut.The portion of metal l5d separating the two channels is preferably ofinwardly decreasing thickness. Instead of the bits being retained inposition by means of a wedge or key, as previously described, themodification shown in Figure 6 comprises the use of a bolt [8 whichpasses through the shanks of the two bits and also passes through thebody of metal l5b which separates the two bits, the head of this boltbeing exposed at the side of the member l5. On the opposite end of thebolt is a nut l9 which is also exposed at the opposite side of themember I5. The shanks of the two bits are provided with holes throughwhich the bolt passes. When the nut I9 is screwed down tight- 1y,pressure is applied to the shanks of the two bits in a transversedirection tending to force the bits into tight frictional engagementwith the walls of the slots l6, and this frictional engagement isincreased by the slight taper in the portion lid which enables theshanks of the bits to be sprung to a very slight extent. In thisconstruction the bits may be removed merely by removing the nut l9 andtaking out the bolt I8. As in the construction previously described, theinner ends of the bits are accessible at the sides of the body l5 sothat after the fastening means is taken out, if the bits still stick,they can be pried out by a working tool inserted between the ends of thebits and the shoulders I50.

In the modification shown in Figures 6, 7 and 8 the arrangement isgenerally similar to that shown in Figures 1, 2 and 3 except that aslightly different construction is provided for holding the cutter bitsagainst endwise movement. In this figure 2a designates the body of theauger and 20 designates the head at the working end of the auger whichcarries the cutter bits 2|, these being generally similar to the cutterbits 5 and 8 of Figure l. The head or body 29 is provided with slots orcavities 23 which open inwardly from the end of the body, the twocavities or recesses 23 terminating in a common opening 24 at theworking end of the head. At the inner end of each of the slots 23 is atransverse opening 25, there being a shoulder 26 at the inner end ofeach of the cavities 23.

The cutter bits 2| are provided on their inner ends with laterallyprojecting lugs 27. Passing transversely through the head is a key slotor opening 28 in which is removably inserted, transversely extending key29.

In this arrangement the cutter bits are inserted endwise into theopening 24, then they are moved laterally into line with theirrespective recesses or cavities 23. Then they are pushed endwise intothe cavities until the lugs 2'! project through the openings 25. Whenthey are in this position the key 29 is driven into place. This wedgesthe inner ends of the bits apart, serving to firmly lock the lugportions 21 in the openings 25 and thus hold the bits against endwisemovement. The key 28 also tends to spring or spread the shanks of thetwo bits apart and thus hold them from chattering during the operationof the drilling. This arrangement avoids any necessity for the accuratepositioning of the key-ways in the shanks of the bits, as required bythe construction illustrated in Figure l and, at the same time, firmlyholds the bits against endwise movement independently of the key 29.This arrangement also enables the shanks of the bits to be sprung by thekey 29 because of the fact that the shanks of the bits do not makecontact with the walls of the cavity throughout the entire length of thecavities 23.

In the several arrangements, which are merely illustrative of thevarious ways in which my invention may be embodied, means passingtransversely through the working head serves to simultaneously lock thebits against lengthwise movement and exert pressure on the bits in atransverse direction for holding them tightly in their sockets andpreventing them from vibrating or chattering or otherwise getting out ofplace. This manner of holding the bits is very effective even though theshanks of the bits are otherwise fairly loose in the slots or openingsin which they are received. At the same time the device is simple andcheap to construct and can be conveniently used in the field.

While I have illustrated and described certain specific embodiments ofmy invention, it will be understood that it may be otherwise constructedand embodied within the scope claims.

1. A bit structure. of the class described comprising. a body member,said member having an opening therein at the end face thereof, whichopening forms a bit-receivingsocket, a cutter bit having a shank portionof rectangular cross section which shank portion is received in thesocket, and means passing transversely through the body and having aninterlockingengagement with the bit for holding. the bit againstlongitudinal movement and constructed to simultaneously exert pressurein a direction normal to the wide faces of the shank of said bit to keepthe bit in tight frictional contact with one wall of the socket.

2. A bit structure of the class described comprising a body member, saidmember having an opening therein at the end face thereof, which openingforms a bit-receiving socket, a cutter bit having a shank portion ofrectangular cross section which shank portion is received in the socket,and means passing transversely through the body and having aninterlocking engagement with the bit for holding the bit againstlongitudinal movement and constructed to simultaneously exert pressurein a direction normal to the wide faces of the shank of the said bit tokeep the bit in tight frictional contact with one wall of the socket,said socket being also open at its inner end whereby access may be hadto the inner end of the shank of the bit for driving it out if the bitbecomes stuck in the socket.

3. A bit structure of the class described comprising a body member, saidmember having an opening therein at the end face thereof, which openingforms a bit-receiving socket, a cutter bit having a shank portion ofrectangular cross section which shank portion is received in the socket,and means passing transversely through the body and having aninterlocking engagement with the bit for holding the bit againstlongitudinal movement and constructed to simultaneously exert pressurein a direction normal to the wide faces of the shank of the said bit tokeep the bit in tight frictional contact with one wall of the socket,said socket terminating at its inner end in a shoulder accessible at theside face of the body and against which the inner end of the shank ofthe bit may abut.

4. A detachable bit structure comprising a body member, said memberhaving a pair of openings extending into it from the end face thereof,said openings being on opposite sides of the 1ongitudinal axis of thebody and forming bit-receiving sockets, there being a partition formedby the body between the two sockets, a pair of cutter bits having shankportions of rectangular cross section, the shank of one bit beingreceived in each socket, and a common securing means passing throughsaid partition for simultaneously holding both bits against longitudinalmovement and which simultaneously applies pressure to both bits in adirection at a point intermediate the ends thereof and in a directionnormal to the wide faces of the shanks for holding the bits in tightfrictional contact with the walls of the socket in which they arereceived to thereby restrain them from chattering.

5. A detachable bit construction comprising a body member for attachmentto the end of an earth-boring auger, said body member having a pair ofopenings extending into it from the end face thereof at opposite sidesof the center of rotation thereof, said openings providing bitreceivingsockets, there being an integral portionof the body providing apartition between said sockets, a cutter bit of rectangular crosssection in each socket, and means passing transversely through the partof the body forming the partition and having an interlocking engagementwith both of the bits arranged to simultaneously hold the bits againstendwise movement and to apply pressure to. the bits in a directionnormal to the width of the bits to increase the frictional contactbetween the bits and one wall of their respective sockets.

6. A detachable bit construction comprising a body member for attachmentto the end of an earth-boring auger, said body member having a pair ofopenings extending into it from the end face thereof at opposite sidesof the center of rotation thereof, said openings providing bit-receivingsockets, there being an integral portion of the body providing apartition between said sockets, a cutter bit of rectangular crosssection in each socket, the portion of said body which is between thesockets having a key-way passing diametrically through it transverse toits longitudinal axis, a wedge in said key-way which bears against thewide faces of both bits, the wedge serving to hold the bits in tightfrictional contact with one wall of their respective sockets, the widefaces of the bits being transversely grooved for interlocking engagementwith the wedge whereby the wedge also locks the bits againstlongitudinal displacement.

7. A detachable bit construction comprising a body member for attachmentto the end of an earth-boring auger, said body member having a pair ofopenings extending into it from the end face thereof at opposite sidesof the center of rotation thereof, said openings providing bit-receivingsockets, a cutter bit of rectangular cross section in each socket, and abolt passing diametrically through the body transversely of thelongitudinal axis thereof and through portions of both of the bits inthe direction of the minimum thickness of the bits, said bolt having anut thereon, said bolt and nut bearing directly against the bits andserving to apply a pressure thereto in a direction transversely of thelongitudinal axis of the body for holding the bits against vibration.

8. A detachable bit construction comprising a body member for attachmentto the end of an earth-boring auger, said body member having spiralflutes thereon to form an extension of the auger, the body having a pairof openings extending into it from the end face thereof, said openingsproviding bit-receiving sockets, the openings being inclined withrespect to the longitudinal axis so that the two sockets cross oneanother, the outer ends of the openings being on opposite sides of thecenter of rotation of the head, the two openings being diagonallypositioned with respect to one another, a bit in each of said socketsprojecting beyond the end of the body, and means passing transverselythrough the body in that portion of the body where the two sockets crosseach other having an interlocking engagement with both of the bits forholding the bits against endwise movement, said means also beingarranged to apply pressure to the bits in a transverse direction forholding the bits in tight frictional contact with the walls of therespective sockets in which they are located.

9. A detachable bit construction comprising a body for attachment to theend of an earth-boring auger, said body having a pair of cavitiesextending into it from the end face thereof, said cavities beingdisposed on opposite sides {'of the center of rotation of the bit, thecavities providing bit receiving sockets, the body having transverseopenings therein at the inner end of each cavity, a bit in each cavityprojecting beyond the end of the body, the inner'end of each bit havinga lug portion that projects through the transverse opening at the baseof its cavity, and means extending transversely through the body forwedging the bits apart in a direction to force the lugs into the saidopenings.

10. An attachment for the ends of earth boring drill bits comprising abody member having two pockets entered into it from an end face thereof,the pockets being of rectangular cross section and terminating atshoulders formed at the inner ends of said pockets by a portion of saidbody, said pockets being operated by an interfitting partition forming apart of said body, a cutter bit having a shank of rectangular crosssection entered into each pocket and having its inner end abuttingagainst the shoulder at the end of the pocket, and means passing throughsaid partition and engaging the shanks of both cutters and applying apressure against the shanks of said cutters normal to the face of theshank which is contacted thereby, thereby tending to press the bitslaterally against the Walls of the pockets to retain them in place andrestrain them from vibrating.

CECIL R. ANDERSON.

Patent nof gglpsflx.

Iti

of the above numbered patent requ im 10, for the word 0nd column, linecla and that the said Letters Patent inthat the same may conform toSigned and sealed this 25rd day of (Seal) CER'II FI GATE OF C ORREC'TION s hereby certified that error 'appe July 8, l9lll CECIL R. ANDERSON.-

should be read with the record of the case September, A. D. l9b l.

Henry Van Arsdale, Acting Commissioner of Patents.

